Chemistry For Life: Developing Fuels

Exothermic: Describes a process which emits energy.

Endothermic: Describes a process which absorbs energy.

Enthalpy Change of Combustion: The process when one mole of a compound is completely burnt in excess oxygen.

Enthalpy Change of Formation: The process when one mole of a compound is formed from it's elements in their standard states.

Enthalpy Change of Reaction: The energy change at a constant pressure and a stated temperature for a process in which a specified amount of reactants are converted into products.

Entropy: The measure of the number of ways particles can be arranged.

Catalyst: A substance which changes the rate of a chemical reaction without undergoing any change itself.

• Exothermic reactions give out heat and have negative enthalpy changes.

• When a reaction gives out heat the chemical reactants are losing energy so the products end up with less energy than what the reactants had.

• Endothermic reactions take in heat and have positive enthalpy changes.

• In an endothermic reaction the reactants take in energy from their surroundings so the products end up with more energy than what the reactants had.